As computers and related equipment are made with greater capacity for more complex tasks, the internal components, in these computers and other components, have been downsized necessarily so that more and more components can be crowded into the same overall computer container. For example, the capacitor developed by Michael Faraday in the form of a Leyden jar has been reduced in size to that of a grain of salt. FIGS. 1A and 1B (generically FIG. 1) show exemplary respective components 10a and 10b (generically components 10). With reference to FIG. 1A, a typical capacitor component 10a is in the form of a rectangular parallelepiped of a length of 0.02 inch (0.51 mm), a width of 0.01 inch (25 mm), and a height of 0.03 inch (0.76 mm), e.g., over 33 of these components placed end to end, would measure almost one inch (25.4 mm).
Greater details of the external and internal structure of a typical component are shown in U.S. Pat. No. 5,226,382 (the '382 patent) of Braden. After the components 10 are first manufactured, their electrical contact surfaces at ends 12a (or the sides) of component 10a are coated with a thin layer of solder paste 14a that also covers small adjacent portions of the sides. The solder paste 14a, also called a “termination,” contains ingredients that upon firing at elevated temperatures render it hard, easy to handle, and easy to reheat for a solder connection to copper strikes on a circuit board. The process of coating and firing components 10 is called a “termination” process. FIG. 1B shows multi-element or array component 10b that has multiple discrete lines of solder paste 14b1, 14b2, and 14b3 (generically 14b) applied across discrete electrical contact surfaces on end 12b (or the sides) in contrast to surfaces that can be coated on the entire end 12a or on any portion thereof.
FIG. 2A is plan view of a prior art carrier belt 20, and FIG. 2B is a cross-sectional view of a prior art carrier mask 22 that is molded onto carrier belt 20. With reference to FIGS. 2A and 2B, a conventional method of high-speed termination employs a continuous metal carrier belt 20 having a plurality of edges 23 that define laterally elongated apertures 24 formed therein that host a like plurality of masks 22 that are molded onto carrier belt 20 from silicon rubber and held by its molded flanges 30. The components 10 are loaded in vertical orientation in component holes 26 in masks 22 with their respective ends 12 (or sides) exposed above and below masks 22. The process employs drive spoke wheel holes 28 to advance the chip-loaded belt 20 to a dipper or “dauber” station where carrier belt 20 is slightly deformed to move one end 12 (or side) of components 10 into contact with termination paste and thereafter pass components 10 through an oven to set the paste before applying the paste to the other end 12 (or side) of the components 10 as disclosed in detail in the '382 patent.
Belt-based termination systems are commonly used in the passive electronic component industry. The cost of replacing belts 20 is a significant portion of the overall operating cost of belt-based termination systems. Each new type of geometry for components 10 may require differently sized masks to hold them. Manufacturers with a high mix of component geometries may require frequent belt changes. The cost of a new endless belt 20 with newly sized masks 22 is significant, and the downtime encountered in changing and tuning new belts 20 takes away from production time and adversely affects throughput and price. Taking belts 20 on and off for temporary belt substitutions can also damage the belts 20, making them useless or adversely affecting the quality of the parts processed on them.
Alternatively, employing the same mask 22 and belt 20 combination for a variety of component designs and sizes reduces the overall quality of the termination process primarily because sharp-edged components 10 tend to cut, shave, or otherwise fray the holding surfaces of the masks 22. Once such damage is done, slightly smaller components 10 or those having a slightly altered body shape are generally not held in masks 22 with sufficient force to avoid misalignment or loss of components 10. Masks 22 will also wear out even if they are used only to hold a single type of component 10, and neither masks 22 nor belts 20 are inexpensive to replace.
Re-masking of a belt 20 with new masks 22 presents its own set of problems. The costs of physically cutting away the old mask makes labor costs high and is a source of physical damage to the typically thin stainless steel belt 20 from an errant knife cut or unintentional creasing. Dissolving away the old mask is possible; however, the solvent and the rubber-solvent solutions are not inexpensive and are candidates for environmental problems in storing and discarding the material. Typically, used belts 20 are discarded.
In addition to mask wear issues, typical mask material must be sufficiently elastic to releasably hold components 10, but such elasticity is nearly incompatible with desired alignment tolerances for holding certain types of components 10, such as multiple element or array components 10b, within masks 22 for processing with greater precision and incompatible with increases in the number of rows 30 of holes 26.
Alignment of the belt 20 to processing stations is typically accomplished by aligning the drive holes 28 to the processing station. Unfortunately, this method of alignment necessitates tight alignment tolerances on the drive holes 28, drive wheels, pulleys, walking beams, and/or other belt translation devices, and processing stations and necessitates labor-consuming alignment of the processing stations to each other. Such alignment requirements increase wear, cost of the equipment, and setup and realignment time, and decrease equipment processing speed and overall throughput. Despite such expensive alignment procedures, components 10b often suffer from misalignment of respective pairs of contact pads 16b1, 16b2, and 16b3 (generically 16b) of solder paste 14b such that components 10b cannot be simultaneously functionally and squarely seated in a circuit board.